xhci: Allocate separate command structures for each LPM command

Every lpm commmand, both for USB 2 and USB 3 devies used the same
xhci->lpm_command structure to change max exit latency.

xhci->lpm_command is only protected by a hcd->bandwidth mutex, which is
not enoungh as USB 2 and USB 3 devices are behind separate HCDs.

Simplify code and avoid unnecessary locking risks by allocating
separate command structures for each lpm command, just like with
all other commands.
Signed-off-by: NMathias Nyman <mathias.nyman@linux.intel.com>
Link: https://lore.kernel.org/r/20220216095153.1303105-7-mathias.nyman@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/host/xhci-mem.c

@@ -1846,9 +1846,6 @@ void xhci_mem_cleanup(struct xhci_hcd *xhci)
 	xhci->event_ring = NULL;
 	xhci_dbg_trace(xhci, trace_xhci_dbg_init, "Freed event ring");
 
-	if (xhci->lpm_command)
-		xhci_free_command(xhci, xhci->lpm_command);
-	xhci->lpm_command = NULL;
 	if (xhci->cmd_ring)
 		xhci_ring_free(xhci, xhci->cmd_ring);
 	xhci->cmd_ring = NULL;
@@ -2488,10 +2485,6 @@ int xhci_mem_init(struct xhci_hcd *xhci, gfp_t flags)
 			"// Setting command ring address to 0x%016llx", val_64);
 	xhci_write_64(xhci, val_64, &xhci->op_regs->cmd_ring);
 
-	xhci->lpm_command = xhci_alloc_command_with_ctx(xhci, true, flags);
-	if (!xhci->lpm_command)
-		goto fail;
-
 	/* Reserve one command ring TRB for disabling LPM.
 	 * Since the USB core grabs the shared usb_bus bandwidth mutex before
 	 * disabling LPM, we only need to reserve one TRB for all devices.

drivers/usb/host/xhci.c

@@ -4344,6 +4344,10 @@ static int __maybe_unused xhci_change_max_exit_latency(struct xhci_hcd *xhci,
 	unsigned long flags;
 	int ret;
 
+	command = xhci_alloc_command_with_ctx(xhci, true, GFP_KERNEL);
+	if (!command)
+		return -ENOMEM;
+
 	spin_lock_irqsave(&xhci->lock, flags);
 
 	virt_dev = xhci->devs[udev->slot_id];
@@ -4360,10 +4364,10 @@ static int __maybe_unused xhci_change_max_exit_latency(struct xhci_hcd *xhci,
 	}
 
 	/* Attempt to issue an Evaluate Context command to change the MEL. */
-	command = xhci->lpm_command;
 	ctrl_ctx = xhci_get_input_control_ctx(command->in_ctx);
 	if (!ctrl_ctx) {
 		spin_unlock_irqrestore(&xhci->lock, flags);
+		xhci_free_command(xhci, command);
 		xhci_warn(xhci, "%s: Could not get input context, bad type.\n",
 				__func__);
 		return -ENOMEM;
@@ -4390,6 +4394,9 @@ static int __maybe_unused xhci_change_max_exit_latency(struct xhci_hcd *xhci,
 		virt_dev->current_mel = max_exit_latency;
 		spin_unlock_irqrestore(&xhci->lock, flags);
 	}
+
+	xhci_free_command(xhci, command);
+
 	return ret;
 }
 
@@ -4510,18 +4517,8 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
 			exit_latency = xhci_besl_encoding[hird];
 			spin_unlock_irqrestore(&xhci->lock, flags);
 
-			/* USB 3.0 code dedicate one xhci->lpm_command->in_ctx
-			 * input context for link powermanagement evaluate
-			 * context commands. It is protected by hcd->bandwidth
-			 * mutex and is shared by all devices. We need to set
-			 * the max ext latency in USB 2 BESL LPM as well, so
-			 * use the same mutex and xhci_change_max_exit_latency()
-			 */
-			mutex_lock(hcd->bandwidth_mutex);
 			ret = xhci_change_max_exit_latency(xhci, udev,
 							   exit_latency);
-			mutex_unlock(hcd->bandwidth_mutex);
-
 			if (ret < 0)
 				return ret;
 			spin_lock_irqsave(&xhci->lock, flags);
@@ -4549,9 +4546,7 @@ static int xhci_set_usb2_hardware_lpm(struct usb_hcd *hcd,
 		readl(pm_addr);
 		if (udev->usb2_hw_lpm_besl_capable) {
 			spin_unlock_irqrestore(&xhci->lock, flags);
-			mutex_lock(hcd->bandwidth_mutex);
 			xhci_change_max_exit_latency(xhci, udev, 0);
-			mutex_unlock(hcd->bandwidth_mutex);
 			readl_poll_timeout(ports[port_num]->addr, pm_val,
 					   (pm_val & PORT_PLS_MASK) == XDEV_U0,
 					   100, 10000);

drivers/usb/host/xhci.h

@@ -1812,8 +1812,6 @@ struct xhci_hcd {
 	/* slot enabling and address device helpers */
 	/* these are not thread safe so use mutex */
 	struct mutex mutex;
-	/* For USB 3.0 LPM enable/disable. */
-	struct xhci_command		*lpm_command;
 	/* Internal mirror of the HW's dcbaa */
 	struct xhci_virt_device	*devs[MAX_HC_SLOTS];
 	/* For keeping track of bandwidth domains per roothub. */